1. Field of the Invention
The present invention relates generally to an electrical evaporator for use with liquid formulations containing a chemical active such as an insecticide, a fragrance, an odor eliminator, or the like, and, in particular, to an electrical evaporator having an adjustable intensity feature that enables variation of the evaporation rate of the liquid formulation between a minimum and maximum level.
2. Description of the Related Art
Electrical evaporators in which the evaporation rate of a liquid formulation from a wick can be adjusted by varying the relative positions of a heating device and the wick are known.
For example, Spanish Utility Model No. 1 005 422 discloses an evaporator in which a heating device and a wick can be moved vertically relative to one another by means of a mechanical device, such as a screw/nut thread mechanism, in order to increase or decrease the heat intensity to which the wick is exposed. European Patent Publication No. 0 942 648, by contrast, discloses an evaporator in which a heating device remains stationary while a wick and bottle are displaced vertically in the direction of the longitudinal axis of the wick using a screw/nut thread mechanism, thereby increasing or reducing the overlap between the wick and the heating device. Still another type of evaporator is disclosed in European Patent Publication No. 0 943 344. In that evaporator, a heating device is mounted on a plug which can be moved toward or away from a wick. A drawback of all of these known devices, however, is that they are relatively expensive to manufacture, due in part to the complex screw/nut thread mechanisms of the first two evaporator types and the specially-designed plug of the third evaporator type.